This invention relates to a new chemical process for making cyclic ethers and diethers having five or six atoms in the ring structure. This new process is applicable to the preparation of cyclic ethers such as tetrahydrofuran, p-dioxane, tetrahydropyran, and phthalan.
In the past, such ethers have been made by dehydration of a corresponding diol, by dehydroacyloxylation of a monoester of the diol, or by the reaction of a dihalide or halo alcohol with a strong base. These known processes have a number of disadvantages including intricate process equipment with substantial recycle of reactants, the production of relatively large volumes of inorganic salt by-product, and separation of the cyclic ether product from an aqueous reaction mixture.
It has been shown that a vicinal epoxide is formed by the thermal decomposition of a .beta.-haloalkyl alkyl carbonate in the presence of a quaternary ammonium or phosphonium salt, see Renga et al., "Process for Making Vicinal Epoxides", Ser. No. 095,002, filed Nov. 16, 1979, now U.S. Pat. No. 4,261,906. It is also known that a linear aromatic alkyl ether is produced by the reaction of an aromatic alkyl carbonate with an alkyl halide in the presence of the same kind of quaternary salt catalyst, see Renga, "Process for Making Aromatic Ethers", Ser. No. 187,688, filed Sept. 16, 1980.